Plastic explosive mixture



Patented July 12, 1932 UNITED STATES PATENT ol-Flor.

PLASTIC, nxrrosrvn mxrunn No Drawing. Application flledrltay 17, 1929,Serial No. 363,999, and in Switzerland May 24, 1928.

onating not without danger.

Within the last few years, pentaerythrite tetranitrate has been usedeither in the form of highly compressed charges for projectiles or asloose crystalline mass for filling detfuzes. This method of employmenthas the disadvantage for projectile charges, that the compressionprocess, owing to the small volume density of pentaerythritetetranitrate of 0.2 to 0.3, is inconvenient an On the other hand it isnot possible in filling detonat-ing fuzes, to reach high pressuredensities and at the same time high detonation speeds, as such explosivecores always need a comparatively thin, flexible sheathing. Seeinghowever that for both modes of employment, as great a density aspossible is required, if nitropentaerythrite is to display its uniqueadvantages as a shattering explosive, a liquefying process would alsocome into question 1n adp but owing to the and the attendant cannot beconsiddition to the compression, high melting point of 141 risk ofdecomposition, this ered.

It has been found that the consolidation of pentaerythrite tetranitratecan be effected easily and without danger by an addition of 10 tonitroglycerine or another homologous liquid nitric acid ester such asfor instance glycol dinltrate by itself or mixed with with 20 parts byweight In such a case use is advisably made of a nitropentaerythrite infine subdivision, such as is precipitated in the form of short, fine'crystals for instance by pouring the stabilized acetone solution intohot water. For instance by simply kneading 80 parts by weight ofnitropentaerythrite of nitroglycerine or nitroglycerine glycoldinitratemixture, a homogeneous granular-plastic mass is rapidly obtained, theinitial density of 1.2 of which can .be brought to the shock-proofmaximum of 1.74 by a pressure of 500-600 kg/cm; whereas purecrystallized pentaerythrite tetranitrate requires for this purpose atleast 3000 kg/cm in four stages and owing to its brittleness makes themoulding out of cavities for detonating caps and detonators diflicult orimpossible. A further advantage of the 80/20% mixture comnitroglycerine.

pared with nitropentaerythrite alone consists in this that with aninvariable detonation velocity, owing to the content and excess ofoxygen of the nitroglycerine, an increased explosive power is obtained,viz. 1450 as compared with 1403 calories per kg. As pentaerythritetetranitrate is somewhat soluble in nitroglycerine with a slightthickening and phlcgmatizing of the same, the two explosives very easilybecome moistened and the crystals stick together thoroughly to form asolid mixture which cannot be separated even when heated, and thesensitivity of which to percussion, pressure and ignition is less ascompared with the constituents of the mixture. An 80/20% mixture ofnitro entaerythrite and nitroglycerine can stillbe detonated so easilyhowever that 0.2 grms. lying freely on sheet iron are caused to explodewith unaralleled shattering power by 0.4 grms. lead azide. The explosiveaction, more especially the local perforating power is greater than thatof any compressible combination hitherto known. With a higher percentageof nitroglycerine however, say 30% and more, the ignition capacity withrespect to lead azide and the per crating power of the mixture' arediminished considerably to a remarkable degree.

As compared with the compressed fillings of crystalline pentaerythritetetranitrate, there is the practical advantage that owing to theplasticity of the mixture, increased charging volumes are possible evenwith far less pressure, which is important more especially in the caseof charges for thin-walled detonating caps and detonators.

What I claim is:

j A plastic explosive composition detonating with great velocity andenergy, consisting of to 90 parts byweight of pentaerythritetetranitrate in a finely crystalline form and 30 to 10 parts by weightof substances selected from agroup consisting of glycol dini trate,nitroglycerine and homologous substances.

In testimony whereof I have afiixed my signature.

' STETTBACHER.

